DE102016105039B4 - Touchable glass or glass ceramic element with reduced light scattering and / or light deflection and method for its production - Google Patents

Abstract

Touchable glass or glass ceramic element (1), comprising a smooth upper side (11), wherein a surface is designated as being smooth, which does not have structures with a height of more than 0.05 mm, and a structured underside (12), wherein the structures (2) of the underside (12) at least in a region (4) of the glass or glass ceramic element (1) with a reduced light scattering and / or light deflection with a dielectric substance (3) are only partially filled, so that the average structure height hder structured bottom (12), indicated as the average of the distance between the lowest and the highest point of the surface profile of the underside (12), after introduction of the dielectric substance (3) between 5% and 95% of the average structural height h of the structured underside (12) Introducing the dielectric substance, and wherein the relative dielectric constant ε of the glass or glass ceramic element (1) before the introduction n of the dielectric substance (3) and the relative permittivity ε of the glass or glass ceramic element (1) do not deviate from one another by more than 10% after the introduction of the dielectric substance.

Description

Field of the invention

The invention relates to glass or glass ceramic elements, for example hobs made of glass or glass ceramic, which have a smooth upper side and a structured lower side and in at least one area a reduced light scattering and / or light deflection. Another aspect of the invention relates to a method for producing such glass or glass ceramic elements.

Background of the invention

Glass or glass ceramic elements which have a smooth first side and a structured second side have been known for a long time. For example, find such structured on one side glass or glass ceramic elements use as a structural glass, for example, in doors or windows, which only translucent effect, but should not allow a clear view of underlying areas.

Furthermore, such elements are also known as cooking surfaces, for example, as cooking surfaces of glass ceramic. In such glass or glass ceramic cooking surfaces often the side which faces away from the user, formed genoppt. This is because in this way the handling of the cooking surfaces is facilitated. Thus, the nub structure of the underside prevents a strong reduction in the strength of the glass or the glass-ceramic due to scratches or other damage to the underside. In contrast, both sides smoothly trained glasses or glass ceramics are much more susceptible to damage during handling such as scratches and require in the production process, for example, in the production of household appliances, a much greater care.

Even though glasses or glass ceramics which have a dimpled underside have clear advantages in handling as well as in the resulting strength, for example against a shock load from above, they also have a number of disadvantages. In particular, the viewing from above on elements located beneath the cooking surface, for example electro-optical display elements such as displays, is limitedly possible due to the structure located on the underside of the glass or glass ceramic element. Thus, in such structured glass or glass ceramic elements, the integration of high-resolution electro-optical display elements, ie, for example, displays with a high so-called dot density, not possible.

Especially with the integration of modern displays continues to play not only the review by a transparent cover, such as glass or glass ceramic, a role that also allows the use of high-resolution optics. Rather, the question of the color location of the figure also plays a role. Thus, there is an increasing need to realize multi-colored displays. However, glass ceramics are often transparent in that they are at least partially transmissive to electromagnetic radiation in the visible light, ie at wavelengths between 380 nm and 780 nm, but have a black color in supervision and a browning in color transmission on. When using colored displays or lighting with a neutral color location, such as white LEDs, this leads to an undesirable color change.

Increasingly important is the integration of touch sensors, for example, capacitive touch sensors, for the operation of cooking surfaces. For this purpose, the dielectric properties of the cooking surface forming glass or glass ceramic element are of particular importance.

In order to enable cooking surfaces with easier handling while at the same time having a good view of, for example, display elements such as displays, in particular high-resolution displays, a number of measures are proposed in the prior art. Also, regarding the change of the color of displays, the prior art presents different solutions.

For example, the U.S. patent application discloses US 2014/251977 A1 a cooking surface which is formed knobbed on the underside, and further in a region, preferably at the edge, has a flat facet. This flat facet has an angle of 2 to 6 ° with respect to the original surface and is obtained by grinding the nubs and subsequent polishing. In the area of the flat facet, the attachment of a high-resolution display can take place. The mechanical polishing of the cooking surface is to be classified as a very complex process. Furthermore, such a mechanical post-processing also always carries the risk of introducing mechanical Damage to reduce the strength of the cooking surface. Furthermore, the removal of the nubs does not change the color locus of the glass ceramic.

The German property right DE 41 04 983 C1 discloses a transparent article having profiling or structuring on at least one side, and a viewing window. In this window, the view through the transparent object, which may be formed, for example, as a glass or glass ceramic disc, compared to the other areas of the article improved. This is achieved by the filling of the profiling at least in the region of the object in which the viewing window is arranged. In principle, any mass is suitable for filling the profiling, as long as it is transparent. Thus, the mass also does not visually filter, but the color location of the filled area remains substantially the same as that of the unfilled area of the object. By way of example, the mass may consist of a thermoplastic material which is laminated onto the profiling. Furthermore, it is also possible that a silicone resin is used as the mass. The mass is applied so that the profiling is completely covered. Consequently, the application of the profiling filling mass also causes an increase in the thickness of the object, such as a disc causes.

The German property right DE 44 24 847 B4 discloses a device for displaying information and operating states on devices, for example on cooking appliances, which have transparent surface areas of glass or glass ceramic. In 1 of the DE 44 24 847 B4 In this case, a mass 2 is applied to the dimpled underside 3 of a glass ceramic. In this mass 2, the attachment 1 of the display unit 4 was inserted while still wet. The mass 2 serves to fill the nubs, so that a viewing window is obtained in which the display capability is improved. Here too, however, the mass 2 is applied in a thickness such that the structures of the underside, here the knobs, are completely filled and covered. This results in particular from the fact that in the still moist mass 2, the attachment 1 can be inserted and thus acts as a kind of "adhesive layer". Thus, the thickness of the glass ceramic is increased by the mass 2 or "immersion layer" in this case. Furthermore, the immersion layer has no optically filtering effect.

In the German patent application DE 103 09 225 A1 is a household appliance disclosed which has a symbol display with light source and an optical filter. The optical filter is formed as a colored film and adhered with an adhesive layer to a lighting component. Between the lighting component and a windshield, a distance of 1 to 2 mm is realized.

Furthermore, different maskings are mounted on the windscreen and the lighting unit. Thus, although an optical filter disclosed here, but no method is described, with which the review would be improved by a disc which is provided on at least one side with a profiling.

Furthermore, the US patent application discloses US 2014/146538 A1 a display device which consists of a glass ceramic with a display side and a side which is illuminated, and a luminous element. The illuminated side can be formed structured, wherein in the area that is illuminated, a leveling layer is applied so that a smooth surface is formed in this area. On this smooth surface, a color filter layer is applied. Furthermore, additional elements may be applied here between the compensating layer and the color filter layer or on the color filter layer, which may act as masking, for example. Again, however, the compensation layer is significantly thicker than the structural height of the glass ceramic. Furthermore, no statements are made about the dielectric properties of the display element thus produced.

The German patent application DE 10 2011 050 870 A1 describes a display device with a transparent colored glass ceramic, which has a front side display and a rear lighting side. On the glass ceramic, a light compensation filter in the form of a color layer is applied.

The German patent application DE 40 07 971 A1 describes a device for switching electrical devices, in particular of cooktops, which is characterized in that a light emitter and a light receiver are arranged under a sufficiently transparent in the transmission shaft region of the light emitter plate. Roughnesses of the glass ceramic plate are filled with a layer so that a smooth surface is obtained.

Thus, there is a need for a glass or glass ceramic element, which at the same time facilitated handling at least in some areas has a reduced dispersion and further in the continued touchability with conventional capacitive touch sensors that are already used for cooking surfaces, is given.

Object of the invention

It is an object of the invention to provide a glass or glass ceramic element with reduced light scattering and / or light deflection in at least one region, wherein the glass or glass ceramic element can be operated with a capacitive touch sensor. Another aspect of the invention relates to a method for producing such a glass or glass ceramic article.

Summary of the invention

The invention is achieved in a surprisingly simple manner by a glass or glass ceramic element according to claim 1 and a method according to claim 13. Preferred embodiments can be found in the respective dependent claims.

The touchable glass or glass ceramic element according to the invention has a smooth upper side and a structured underside, the light scattering and / or light deflection of the structures of the underside being reduced in at least one area.

For the purposes of the present invention, light deflection is understood to mean the optical, refractive light deflection which occurs, for example, in the case of optical elements such as lenses. In this sense, a light deflection can result on a nubby underside of a glass ceramic through the nub structures of the underside, which is similar in each case at the location of a nub to that of a convex / concave optical element.

Not the term "light deflection" in the sense of the present invention is intended to mean a deflection of the light which is caused only by the passage of the light into a medium with a different refractive index on the otherwise flat, in particular smooth surfaces.

The advantage here is the higher sharpness of contours in view, which is accompanied by the reduced light scattering and / or light deflection, for example a display such as a 7-segment display.

In the context of the present invention, a surface is then referred to as smooth, which in itself has no structures with a height of more than 0.05 mm. In this case, "in itself" means that the surface formed from the glass or the glass ceramic itself has only smaller structural heights than 0.05 mm, wherein the structural height is indicated here as the average structural height, ie as the mean value of the distance to the respectively lowest and the respectively highest point of the surface course of the individual structures. However, the upper side of the glass or glass ceramic element according to the invention may additionally have further structures which have been imprinted from this surface after shaping, for example in the form of coatings applied to the surface. Likewise, the upper side can have local depressions and / or elevations which have been produced, for example, by mechanical or thermal processes, preferably by laser processes, in or on the upper side. In these local depressions and / or elevations, the structure height can also be more than 0.05 mm, preferably between 0.02 mm and 0.8 mm, particularly preferably between 0.05 mm and 0.2 mm. The locally reformed region preferably comprises less than 20% of the total surface area of the upper surface, more preferably less than 10%.

The structures of the underside of the glass or glass ceramic element according to the invention are only partially filled with a dielectric substance in at least one region which has reduced light scattering and / or light deflection. In this way, the average structure height h corresponds to _n after introduction of the dielectric substance between 5% and 95% of the average structure height h _v of the structured bottom before introducing the dielectric substance. The average structural height h _n is preferably between 5% and 60% and particularly preferably between 15% and 50% of the structural height h _v . Furthermore, the relative dielectric constant ε _{R, v of} the glass or glass ceramic element of the present invention and the relative dielectric constant ε _{R, n} after introduction of the dielectric substance by not more than 10%, preferably not more than 5%, from each other.

In the glass or glass ceramic element of the present invention, therefore, the introduction of the dielectric substance is carried out so that the structure valleys are partially filled with the substance. In contrast, the tips of the structure have a significantly lower occupancy with the dielectric substance. Thus, the total thickness of the glass or glass ceramic element by the introduction of the dielectric substance is not or only to a very limited extent. Thus, the thicknesses of such glass or glass ceramic elements of the invention differ from those of glass or glass ceramic elements in which there has been no only partial filling of the structures, only in the same order of magnitude, in the usual manufacturing tolerances for the thickness of glass or Glass ceramics lie. These tolerances are usually in the range of 0.1 mm or less.

Although the filling of the structures with the dielectric substance does not take place in such a way that a completely smooth surface of the thus treated underside is obtained, it has surprisingly been found that nevertheless a clearly improved view is achieved by the glass or glass ceramic element. In particular, the reduced so-called reduction in transparency is sufficient to enable high resolution displays with a pixel density of up to 210 dpi (dots per inch).

According to one embodiment of the invention, the structure tips of the structured underside are not covered with the dielectric substance.

According to a further embodiment of the invention, an electro-optical display device is arranged below the area with reduced light scattering / light deflection. This is preferably a display, particularly preferably a display which has a resolution with a pixel density of up to 210 dpi (dots per inch).

According to a further embodiment of the invention, the dielectric substance in the wavelength range from 380 nm to 780 nm has a transmission for electromagnetic radiation of at least 80%, preferably of at least 90%. By applying the dielectric substance, the transmission for electromagnetic radiation in the wavelength range from 380 nm to 780 nm thus changes only very slightly and differs from that of a glass or glass ceramic element which has no such substance by at most 5 percentage points.

The dielectric substance preferably has a temperature resistance of at least 250 ° C., preferably of at least 270 ° C., for a short time at 300 ° C., and a continuous capacity of at least 300 h at 100 ° C., preferably at least 400 h at 100 ° C., and more preferably of at least 500 h at 100 ° C. The temperature resistance is determined here by comparing the transmission for electromagnetic radiation in the wavelength range from 380 nm to 780 nm before and after a thermal load. The maximum difference of the transmission values before and after thermal loading is at most 5 percentage points.

Preferably, the dielectric substance is formed as a silicone resin. Still more preferably, the silicone resin has functionalized organic groups. As functionalized organic groups, e.g. Modifications by polyesters, polyacrylates, epoxies, vinyls, acrylates, methacrylates, alkanes can be used. However, the dielectric substance may also be in the form of other transparent materials, e.g. Polyacrylates, polycarbonates, polymethacrylates, Optical Clear Adhesives, the latter e.g. from the company 3M.

The advantage of silicone resins or silicones lies in their high elasticity. This is created by the freely movable chains over high degrees of rotation, translation and vibration. These compensate for tensile stresses caused by mechanical influences or during drying of the layer on the substrate and thus avoid cracking.

Also preferred are dielectric substances which have the same refractive index as the glass or the glass ceramic.

According to one embodiment of the invention, the dielectric substance is present as a layer with a maximum layer thickness between 60 μm and 100 μm, preferably between 70 μm and 90 μm. Such high maximum layer thicknesses are particularly preferred because in this way even structures with structural heights of more than 100 microns can be compensated. The layer formed from the dielectric substance in this case has a thickness which varies over the spatial extent of the layer, depending on whether the layer is present on a structure top or in a structural valley. In this case, the maximum thickness is defined as the layer thickness which forms the layer formed from the dielectric substance into the layer Structured valleys. In the context of the present invention, a layer or coating is understood as meaning a structure made of a material, the material being brought onto a substrate and covering a coherent, spatially delimited area of this substrate.

In the context of the present invention, the terms layer and coating are used synonymously.

According to a further embodiment of the invention, the surface of the dielectric substance has a surface energy between 20 mN / m and 40 mN / m, preferably between 30 mN / m and 35 mN / m. This corresponds to a contact angle of 80 ° to water, 62 ° to ethylene glycol and 51 ° to diiodomethane.

The polar fraction of the surface energy is preferably less than 15 mN / m, preferably less than 8 mN / m. The polar component of the surface energy is the proportion which is attributable to polar interactions of the molecules, that is, for example, to permanently existing dipole moments. On the other hand, the dispersive component of the surface energy is due to transient fluctuations of the electron density (so-called London forces). With devices which are mounted below the bottom of the layer, such as contact elements, display elements, such as high-resolution displays, there is no undesirable (chemical) reaction or interaction at higher temperatures (eg 100 ° C / 40 h). The components in the display and / or operating area can thus be detached from this coated glass or glass ceramic element with virtually no residue. According to a particularly preferred embodiment of the invention, the dielectric substance furthermore comprises at least one dye and / or one pigment. The pigment has a particle size with a d ₅₀ of 100 nm or less. Preferably, the dye and / or the pigment are formed so that the respective absorption coefficient for electromagnetic radiation in the wavelength range of 530 nm to 630 nm is less than in the wavelength range of 380 nm to 530 nm and in the wavelength range 530 nm to 780 nm. The pigment and / or the dye thus impart a blue or bluish tint to the dielectric substance.

Such an embodiment is particularly preferred in particular if the intrinsic color of the glass or glass ceramic element is to be compensated by such a dielectric substance which has been applied, for example, as a layer to the glass or glass ceramic element. If, for example, the glass ceramic element is colored orange-brown in transmission, then white or blue light of a light source, which is arranged behind the glass ceramic as seen by the observer, is not perceived as white or blue. The blue or bluish coloring of the dielectric substance makes it possible to compensate for the intrinsic color of the glass ceramic, so that, for example, white light is also perceived as such.

According to yet another embodiment of the invention, at least one further layer is in contact with the dielectric substance.

In this case, the at least one further layer is preferably formed as a color compensation layer and / or as a masking layer and / or as another functional layer. For example, the further layer may be formed as an electrically conductive layer.

• - Bereitstellen eines Glas- oder Glaskeramikelements, welches eine glatte Oberseite sowie eine strukturierte Unterseite aufweist. Dabei beträgt die Strukturhöhe h_v der Unterseite vor der Durchführung des Verfahrens zwischen 80 µm und 120 µm.
• - Bereitstellen eines Lackes, welcher eine Viskosität zwischen 1500 mPas und 2500 mPas, bevorzugt zwischen 1900 mPas und 2300 mPas, bei einer Temperatur von 25°C aufweist.
• - Aufbringen des Lacks. Der Lack wird in zumindest einem Bereich der Unterseite des Glas- oder Glaskeramikelements so aufgebracht, dass in diesem Bereich die Strukturtäler zumindest partiell aufgefüllt werden.
• - Aushärten des Lacks. Der Lack wird dabei so ausgehärtet, dass in dem mit dem Lack belegten Bereich eine dielektrische Substanz vorliegt, welche die Strukturtäler der Struktur lediglich partiell ausfüllt, sodass die mittlere Strukturhöhe h_n der Struktur der Unterseite nur noch zwischen 5 % bis 95 %, bevorzugt zwischen 5 % und 60 % und besonders bevorzugt zwischen 15 % und 50 % der Strukturhöhe h_v vor Einbringen der dielektrischen Substanz beträgt.

The glass or glass ceramic element according to the invention can be obtained by a process comprising the following steps:

• - Providing a glass or glass ceramic element, which has a smooth top and a textured bottom. In this case, the structural height h _{v of} the underside before the implementation of the method is between 80 μm and 120 μm.
• - Providing a paint, which has a viscosity between 1500 mPas and 2500 mPas, preferably between 1900 mPas and 2300 mPas, at a temperature of 25 ° C.
• - Applying the paint. The paint is applied in at least one region of the underside of the glass or glass ceramic element so that the structural valleys are at least partially filled in this area.
• - curing of the paint. The paint is cured so that there is a dielectric substance in the area covered with the paint, which only partially fills the structural valleys of the structure, so that the average structural height h _{n of} the structure of the underside is only between 5% to 95%, preferably between 5% and 60% and more preferably between 15% and 50% of the structural height h _v before introduction of the dielectric substance.

In this case, in the period between the application of the paint and before its curing, the degree of filling of the structure valleys also be 1, so the structure is completely filled by the paint. The curing of the paint but it comes to shrinkage processes, for example by the evaporation of one or more solvents, so that after curing, the structure valleys are only partially filled.

As a paint is understood in the context of the present application, a liquid coating composition. From this varnish, the dielectric substance is then produced as part of a physical and / or chemical curing process, i. the dielectric substance can be understood to be producible from a cured lacquer (or hardened coating agent).

The curing of the paint can be done thermally, but also by means of IR or UV radiation.

In principle, however, other application methods are conceivable. For example, it is possible to apply the paint by means of other conventional liquid coating methods, for example by means of doctoring, flooding, rolling, spin coating, ink jet or casting.

The application of the lacquer according to an embodiment of the invention is such that the thickness of the dielectric substance applied to the structure tips in the cured state corresponds to between 0% and 25% of the maximum thickness of the dielectric substance in the structure valleys. For example, it is possible that the structure tips are completely uncoated. However, it is likewise possible for the structure tips to have at least partial coverage with the dielectric substance. However, the maximum thickness of this dielectric substance on the structure tips is always less than the maximum thickness of the dielectric substance in the valleys of the structure.

For example, the maximum thickness of the dielectric substance in the structure valleys may be 100 μm. In this case, the maximum thickness of the dielectric substance on the structure tips would be 25 μm; However, it would also be possible that the maximum thickness was only 10 microns. Furthermore, the structure tips could also be completely free of a dielectric substance.

Consequently, according to a further embodiment of the invention, the structure tips do not have an occupancy with the dielectric substance.

According to a further embodiment of the invention, the lacquer comprises between 95% by weight and 99.5% by weight of a silicone resin, preferably of a functionalized silicone resin, and between 5% by weight and 0.5% by weight of at least one surface-active additive , Furthermore, the silicone resin up to 25 wt .-% solvent.

In the context of the present invention, the silicone resin referred to here are compounds in which crosslinkable molecules are present, these molecules having silicon atoms which are linked to one another by oxygen atoms. Furthermore, these substances additionally have organic constituents which are likewise bonded to the silicon atoms, and optionally further organic functional groups. Such a silicone resin is capable of curing under polymerization. Thus, the term silicone resin also includes organic polysiloxanes.

In the context of the present invention, a surface-active additive is understood as meaning a substance which is added to a liquid coating agent in small amounts, that is to say in the range of 5% by weight or less, based on the total mass of the coating agent, in order to reduce the content of bubbles or bubbles Aggregation of bubbles (foam) in the coating to reduce, for example, by the resolution of existing bubbles. In particular, so-called defoaming and deaerating additives are to be understood as surface-active additives for the purposes of the present invention.

In particular, it is possible that not only such a surface-active additive is used, but a mixture of such additives is used. In this case, according to a further embodiment of the invention, the total content of surface-active additives in the paint between 0.5 wt .-% and 5 wt .-%, based on the total weight of the coating composition.

In addition, the paint may contain other additives, such as functionalized silanes and / or silicones.

According to a further embodiment of the invention, the curing of the paint takes place thermally, preferably at a temperature between 150 ° C and 250 ° C. The duration of the curing is preferably between 10 minutes and 2 hours, preferably 0.5 hours to 1 hour.

According to yet another embodiment of the invention, the coating further comprises at least one dye and / or pigment, wherein the pigment has a d ₅₀ of 100 nm or less. The paint preferably comprises a dye and / or a pigment in which the absorption coefficient for electromagnetic radiation in the wavelength range from 530 nm to 630 nm is less than in the wavelength range from 380 nm to 530 nm and in the wavelength range from 530 nm to 780 nm and / or the pigment thus impart a blue color to the paint and / or the dielectric substance resulting therefrom after curing.

Examples

The invention is explained below on the basis of exemplary embodiments.

Embodiment 1

99 g of a polyester-modified silicone resin are mixed with 1 g of a solution of a fluorosilicone, ie a surface-active additive. The resulting paint has a viscosity of 2150 mPas at 25 ° C. The paint was applied by screen printing with a 24er sieve. Subsequently, the curing was carried out at 200 ° C for 1 h.

The resulting layer has a surface energy of 33 mN / m. A mounted below this layer display device shows no light deflection. In particular, the nubs on the underside of the glass ceramic are no longer visible, so that even high-resolution displays with a pixel density of up to 210 dpi can be used. The transmission for electromagnetic radiation in the wavelength range from 380 nm to 780 nm of the glass ceramic occupied by the dielectric substance and the unoccupied glass ceramic deviates by at most 5 percentage points from each other.

Embodiment 2

97 g of a polyester-modified silicone resin are mixed with 3 g of a solution of a fluorosilicone in 2,6-dimethyl-4-heptanone, ie a surfactant additive. The resulting paint at 25 ° C has a viscosity of 2020 mPas. The paint was applied by screen printing with a 24er sieve. Subsequently, the curing was carried out at 200 ° C for 1 h.

The resulting layer has a surface energy of 33 mN / m. A mounted below this layer display device shows no light deflection. In particular, the nubs on the underside of the glass ceramic are no longer visible, so that even high-resolution displays with a resolution of up to 210 dpi can be used. The transmission for electromagnetic radiation in the wavelength range from 380 nm to 780 nm of the glass ceramic occupied by the dielectric substance and the unoccupied glass ceramic deviates by at most 5 percentage points from each other.

Embodiment 3

A particular advantage of the glass or glass ceramic elements according to the invention with only partial filling of the structures is that the thickness of the glass or of the glass ceramic is not changed by the only partial filling of these structures. This thickness results here as a distance between the smooth upper surface of the glass or glass ceramic element and the structural tips of its structured underside. Furthermore, due to the special configuration of the layer, the dielectric properties of the uncoated substrate are not changed or only within the scope of the measuring accuracy of the measuring methods used. This is exemplified by the measured values obtained for Embodiment 3 of the present invention.

In Embodiment 3 (AB 3) is the glass ceramic HighTrans eco, in which the nub structure of the bottom was only partially filled so that only in the structure valleys, the dielectric substance, here exemplified as a silicone resin, is present, but the tips of the Structure, so here the Noppensitzen not occupied with the dielectric substance. The relative dielectric constant ε _R , the loss factor tan δ as well as the resulting capacitance C _p and the corresponding area capacity C _{p /} A determined. These data are shown in the following table. Furthermore, for comparison, the corresponding values for a glass ceramic not coated with a dielectric substance (Comparative Example CE 1) and for a glass ceramic provided with a dielectric coating of the prior art, ie with a dielectric substance completely filling the structures and covering them (Comparative Example VB 2). Table 1 sample thickness ε _R tan δ C _p C _p / A FROM 3 4.09 mm 8.0 ± 0.2 (177 ± 12) * 10 ^-4 23 pF 1.84 pF / cm ² VB 1 3.96 mm 8.2 ± 0.2 (167 ± 12) * 10 ^-4 22 pF 1.72 pF / cm ² VB 2 4.89 mm 6.3 ± 0.2 (113 ± 8) * 10 ^-4 14 pF 1.14 pF / cm ²

The values for the relative dielectric constant as well as for the loss factor were determined here by means of complex impedance spectroscopy at a frequency of 1 MHz. The ALPHA Analyzer from Novocontrol was used for this purpose. The determination was carried out on three samples each, which were coated on both sides with conductive silver for contacting (so-called pseudo-four-point contact). The measurements were carried out at 25 ° C.

It can be seen that the values between the unoccupied reference of Comparative Example 1 and Embodiment 3 differ from one another only within the scope of the measurement accuracy. Although the two samples have a different thickness, but the difference in thickness here is only within the usual manufacturing tolerances for the production of a dimpled glass or glass ceramic disc and is not due to the occupancy of the dielectric substance. The difference in the thickness and the material constants and the surface capacitance between Embodiment 3 and Comparative Example 2, on the other hand, is based on the complete backfilling of the structures of the underside in Comparative Example 2 in contrast to the only partial backfilling of Embodiment 3.

list of figures

Hereinafter, for a more detailed explanation of the invention reference is made to the enclosed figures. In the figures, like reference numerals refer to like or corresponding elements.

• 1 bis 3 Ausführungsformen eines erfindungsgemäßen Glas- oder Glaskeramikelements,
• 4 und 5 Transmissionskurven unterschiedlicher Glaskeramikelemente,
• 6 und 7 topographische Darstellungen der Unterseite erfindungsgemäßer Glas- oder Glaskeramikelemente, sowie
• 8 bis 10 elektronenmikroskopische Abbildungen erfindungsgemäßer Glas- oder Glaskeramikelemente mit partiell verfüllter Struktur.

Show it

• 1 to 3 Embodiments of a glass or glass ceramic element according to the invention,
• 4 and 5 Transmission curves of different glass ceramic elements,
• 6 and 7 Topographical representations of the bottom of inventive glass or glass ceramic elements, and
• 8th to 10 Electronmicroscopic images of inventive glass or glass ceramic elements with partially filled structure.

In 1 is schematic and not true to scale one embodiment of a glass or glass ceramic element according to the invention 1 shown. The glass or glass ceramic element 1 has a top 11 which is smooth. A surface in the context of the present application is then referred to as being smooth if it does not have any structures in it which have a mean structural height h of more than 0.05 mm. The average structure height h is determined here as the mean value of the distance between the respective lowest and the respectively highest point of the surface profile of the individual structures. In this case, "in itself" means that the surface formed from the glass or the glass ceramic itself has only smaller structural heights than 0.05 mm. However, this surface can also have further structures which are not inherent to the surface as such, but have been produced, for example, in a downstream process. Exemplified here are structures which have been produced by a coating.

Furthermore, the glass or glass ceramic element of the present invention has an underside 12 on what structures 2 having. The terms of the top and the bottom of a glass or glass ceramic element refer to the subsequent application of the glass or glass ceramic element. So will in the later application here as a subpage 12 designated surface of the glass or glass ceramic element 1 the side facing away from the user while the top 11 facing the user.

The structures 2 the bottom 12 are exemplified here as nubs. In general, without being limited to the example shown schematically here, other structures, such as grooves or pyramids, may also be present. The structures 2 each have a structure tip 21 on, with this structural tip 21 the highest point of the structure 2 designated, as well as a structural valley 22 , which is between the individual structure tips 21 lies.

Furthermore, the glass or glass ceramic element 1 the area 4 on, which has a reduced light scattering and / or light deflection. In this area are the structural valleys 22 the bottom 12 partially with the dielectric substance 3 filled. This dielectric substance 3 preferably comprises a silicone resin and has a continuous temperature load of at least 500 h at 100 ° C and a maximum temperature resistance of 250 ° C. It is shown by way of example that the structure peaks 21 in the area 4 not with the dielectric substance 3 are covered. In general, without limitation to the example shown here, but also the structural peaks 21 coated present. However, the maximum thickness of the dielectric substance is 3 on the structure tips 21 only between 0% to 25% of the maximum thickness of the dielectric substance 3 in the structural valleys 22 , The thickness of the dielectric substance is preferably 3 between 60 microns and 100 microns, more preferably between 70 microns and 90 microns, said maximum thickness in the structural valleys 22 is present. Thus, the maximum thickness of the dielectric substance is 3 on the structure tips 21 preferably 25 microns, more preferably only 22.5 microns.

Furthermore, it is possible that the dielectric substance 3 comprises a coloring agent, for example, a dye or a pigment, wherein the pigment has a d ₅₀ of 100 μm or less. It is preferably a dye or a pigment which gives the paint a blue or bluish color. In this way, it is possible to compensate for the inherent color of a glass or a glass ceramic element, so that, for example, color-neutral lighting elements can also be perceived as such.

2 also shows schematically and not to scale a representation of a glass or glass ceramic element 1 according to a further embodiment of the invention. In turn, the upper side is indicated 11 and the bottom 12 of the glass or glass ceramic element 1 , The bottom 12 shows the structures 2 on, which are characterized by the structure peaks 21 and the structural valleys 22 and are exemplified here as nubs. In the area 4 are the structural valleys 22 partially with the dielectric substance 3 refilled. The dielectric substance 3 remains in contact with another layer 5 , This further layer 5 is here exemplified as a masking layer. Such a masking layer serves, for example, to ensure that areas adjacent to a lighting element are not backlit by stray light originating from the lighting element. In general, without being limited to the masking example shown here, the layer 5 can also have other functions. For example, the layer 5 be formed as an electrically conductive layer.

3 shows yet another schematic and not to scale representation of another glass or glass ceramic element according to an embodiment of the invention. In turn, the upper side is indicated 11 and the bottom 12 as well as those on the bottom 12 located structures 2 , which structure peaks 21 and structural valleys 22 exhibit. In the area 4 , which is characterized by a reduced light scattering and / or light deflection, are the structural valleys 22 partially with a dielectric substance 3 filled. Here, too, is the dielectric substance 3 in contact with another layer 5 , This layer 5 is here designed as a color compensation layer 5 , In the example shown here, the dielectric substance comprises 3 no colorant such as a dye or a pigment. The function of the color filter rather takes the layer here 5 true.

4 and 5 show transmission curves of different glass ceramic elements with a thickness of about 4 mm, the thickness of these glass ceramic elements can vary by manufacturing up to 0.15 microns by the nominal value of 4 mm. The glass ceramic elements have in part a partial backfilling of the lower structures 2 with the dielectric substance 3 on. The values obtained in the transmission measurement lie in a very narrow range, so that a distinction of the individual transmission curves in the overview diagram of 4 is very difficult.

For that reason shows 5 only a part of the diagram 4 , where the different transmission curves are designated here. The curves 6 and 6a show the Transmittance values, which were obtained for glass ceramic elements, in which there is no backfilling of the structures 2 has come. The curves 7 and 7a are given transmission curves of glass ceramic elements according to the invention 1 , each for one area 4 were determined in which the structures 2 partially filled. The curves 8th and 8a show the transmission for further glass ceramic elements according to the invention 1 and were also for the area 4 determined with reduced light scattering. These glass ceramic elements 1 However, were subjected before transmission measurement, a thermal load of 500 h at 100 ° C.

From the 4 and 5 is thus apparent that the transmission of inventive glass or glass ceramic elements 1 by the filling of the structures according to the invention 2 with a dielectric substance 3 is not changed or only in the context of what is already predetermined by manufacturing tolerances of the glass or glass ceramic elements and / or by the metrological tolerance.

6 shows a topographic representation of the bottom 12 of a glass or glass ceramic element according to the invention in the boundary region between the area 4 with partially filled structures 2 and the area of the untreated bottom 2 , In the lower part of 6 In this case, a schematic cross section through the surface profile is shown. This shows that the occupancy of the structure peaks 21 significantly thinner than the occupancy within the structural valleys 22 , It is only between a maximum of 25% and 0% of the thickness of the occupancy in the structure valleys 22 ,

7 further shows a topographical representation of the bottom 12 in the area 4 in which the structures 2 partially with a dielectric substance 3 have been filled. The structure height is significantly lower than in the case of an unfilled structure 2 as seen in the upper right area of 6 you can see.

8th shows an electron micrograph of a fracture edge of a glass or glass ceramic element according to the invention 1 , Here are the structure tip 21 as well as the two structural valleys 22 , The bottom 12 of the glass or glass ceramic element 1 is here with a dielectric substance 3 which documents the structures 2 the bottom 12 partially filled up.

9 showed a further electron micrograph of a fracture edge of a glass or glass ceramic element according to the invention 1 , Shown and designated here is a structure tip 21 , which with the also designated dielectric substance 3 is occupied. The thickness of this assignment is only less than 10 microns.

10 In contrast, shows an electron micrograph of a fracture edge of a glass or glass ceramic element according to the invention 1 , where here is a structural valley 22 is shown and designated. The structural valley 22 has a backfill with the designated dielectric substance 3 on. The thickness of the dielectric substance 3 in the structural valley 22 is a maximum of about 110 microns. Thus, the ratio of the maximum thicknesses of the dielectric substance is 3 of structure top 21 to structural valley 22 less than 9%. In general, without limitation to the example shown here, it is also possible that the structure tip 21 completely free of an occupancy with the dielectric substance 3 is. Likewise, it is generally possible that the maximum thickness of the dielectric substance 3 on the structure tips 21 up to 25% of the maximum thickness of the dielectric substance 3 in the structural valleys 22 is.

LIST OF REFERENCE NUMBERS

1 -

Glass or glass ceramic element

11 -

Top of the glass or glass ceramic element

12 -

Bottom of the glass or glass ceramic element

2 -

structure

21 -

structure tip

22 -

Strukturtal

3 -

dielectric substance

4 -

Area with reduced scattering

5 -

further layer, for example color compensation layer, masking layer, other functional layer

6, 6a -

Transmission curves of a glass or glass ceramic element without a filled structure

7, 7a -

Transmittance curves of a glass or glass ceramic element in area 4

8, 8a -

Transmission curves of a glass or glass ceramic element in area 4 after temperature load

Claims (19)

Changed claims Touchable glass or glass ceramic element (1), comprising a smooth upper side (11), wherein a surface is designated as being smooth, which does not have structures with a height of more than 0.05 mm, and a structured underside (12), wherein the structures (2) of the underside (12) are only partially filled at least in a region (4) of the glass or glass ceramic element (1) with reduced light scattering and / or light deflection with a dielectric substance (3), so that the mean structure height h _{n of} the structured underside (12), indicated as the mean value of the distance between the lowest and the highest point of the surface profile of the underside (12), after incorporation of the dielectric substance (3) between 5% and 95% of the mean structural height h _{v of} the structured underside (12) before introduction of the dielectric substance, and wherein the relative dielectric constant ε _{R, v of} the glass or glass ceramic element (1) before de m introduction of the dielectric substance (3) and the relative dielectric constant ε _{R, n of} the glass or glass ceramic element (1) after introduction of the dielectric substance by not more than 10% differ from each other. Glass or glass ceramic element (1) according to Claim 1 , wherein the maximum thickness of the dielectric substance (3) on the structure tips (21) is between 0% and 25% of the maximum thickness of the dielectric substance (3) in the structure valleys (22). Glass or glass ceramic element (1) according to one of Claims 1 or 2 , wherein below the area (4) an electro-optical display device is arranged. Glass or glass ceramic element (1) according to one of Claims 1 to 3 , wherein the dielectric substance in the wavelength range of 380 nm to 780 nm has a transmission for electromagnetic radiation of at least 80%. Glass or glass ceramic element (1) according to one of Claims 1 to 4 in which the dielectric substance (3) has a maximum temperature resistance of at least 200 ° C. and a continuous capacity of at least 300 h at 100 ° C., the temperature resistance being determined by comparing the transmission for electromagnetic radiation in the wavelength range from 380 nm to 780 nm, wherein the difference of the transmission values before and after thermal stress is not more than 5 percentage points. Glass or glass ceramic element (1) according to one of Claims 1 to 5 , wherein the dielectric substance (3) is formed as a silicone resin. Glass or glass ceramic element (1) according to one of Claims 1 to 6 , wherein the dielectric substance (3) is present as a layer with a layer thickness between 60 μm and 100 μm. Glass or glass ceramic element (1) according to one of Claims 1 to 7 wherein the surface (31) of the dielectric substance (3) has a surface energy between 20 mN / m and 40 mN / m. Glass or glass ceramic element (1) according to Claim 8 , wherein the polar component of the surface energy is less than 15 mN / m. Glass or glass ceramic element (1) according to one of Claims 1 to 9 wherein the dielectric substance (3) further comprises at least one dye and / or pigment, wherein the pigment has a particle size with a d ₅₀ of 100 nm or less. Glass or glass ceramic element (1) according to one of Claims 1 to 10 wherein at least one further layer (5) is in contact with the dielectric substance (3). Glass or glass ceramic element (1) according to Claim 11 , wherein the at least one further layer (5) is formed as a color compensation layer and / or as a masking layer and / or as another functional layer. Process for producing a glass or glass ceramic element (1) according to one of the Claims 1 to 12 comprising the following steps: - providing a glass or glass ceramic element (1) which has a smooth upper side (11) and a structured lower side (12), wherein the structural height h _{v of} the lower side (12) is between 80 μm and 120 μm Providing a varnish which has a viscosity between 1500 mPas and 2500 mPas at a temperature of 25 ° C., applying the varnish in at least one region (4) of the underside (12) of the glass or glass ceramic element (1) in this area (4) the structural valleys (22) are at least partially filled, - hardening of the lacquer, so that in the region (4) a dielectric substance (3) is present, which only partially fills the structural valleys (22) of the structure (2) so that the average structure height h _n of structure (2) of the bottom (12) only between 5% to 95% of the structural height h _v is. Method according to Claim 13 , wherein after curing of the paint, the maximum thickness of the dielectric substance (3) on the structure tips (21) is between 0% and 25% of the maximum thickness of the dielectric substance (3) in the structure valleys (22). Method according to one of Claims 13 or 14 wherein the varnish comprises between 95% by weight and 99.5% by weight of a silicone resin and between 5% by weight and 0.5% by weight of at least one surface-active additive, and furthermore the silicone resin may contain up to 25% by weight. % Solvent. Method according to Claim 15 wherein the paint further comprises additives. Method according to one of Claims 13 to 16 wherein the curing of the paint takes place thermally. Method according to one of Claims 13 to 17 wherein the lacquer further comprises at least one dye and / or pigment, wherein the pigment has a d ₅₀ of 100 nm or less.

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